This study reports on computational experiments for an agent-based labor market-model-with adaptive choice'and refusal of work site' partners and with endogenously evolving work site behaviors. Two treatment factors ^e experimentally varied: market structure; and ex ante capacity constraints on potential work offers and job openings.- Particular attentions focused on experimentally determined correlations between treatment factors and the formation of contractual networks among workers and employers, and between' contractual network"formation and the'types'o!f work site interactions and welfare outcomes that these contractual networks support.